Details

Autor(en) / Beteiligte

• Spekkens, Kristine
• Giovanelli, Riccardo
• Haynes, Martha P

Titel

The Cusp/Core Problem in Galactic Halos: Long-Slit Spectra for a Large Dwarf Galaxy Sample

Ist Teil von

• The Astronomical journal, 2005-05, Vol.129 (5), p.2119-2137

Ort / Verlag

IOP Publishing

Erscheinungsjahr

2005

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• We derive inner dark matter halo density profiles for a sample of 165 low-mass galaxies using rotation curves obtained from high-quality, long-slit optical spectra assuming minimal disks and spherical symmetry. For r(r) ~ r-a near the galaxy center, we measure median inner slopes ranging from am = 0.22 ± 0.08 to 0.28 ± 0.06 for various subsamples of the data. This is similar to values found by other authors and in stark contrast to the intrinsic cusps (aint ~ 1) predicted by simulations of halo assembly in cold dark matter (CDM) cosmologies. To elucidate the relationship between am and aint in our data, we simulate long-slit observations of model galaxies with halo shapes broadly consistent with the CDM paradigm. Simulations with aint = 1/2 and 1 recover both the observed distribution of am and correlations between am and primary observational parameters such as distance and disk inclination, whereas those with aint = 5/4 are marginally consistent with the data. Conversely, the hypothesis that low-mass galaxies have aint = 3/2 is rejected. While the simulations do not imply that the data favor intrinsic cusps over cores, they demonstrate that the discrepancy between am and aint ~ 1 for our sample does not necessarily imply a genuine conflict between our results and CDM predictions; rather, the apparent cusp/core problem may be reconciled by considering the impact of observing and data-processing techniques on rotation curves derived from long-slit spectra.